Correspondence—J. B. Scrivenor. 139 
On the composition of a stone from the meteoric shower which fell at 
Dokachi, Bengal, on October 22, 1903. The small crusted: stone 
examined, weighing 17:8 grams, shows chondritic structure, and 
belongs to the class Ci of Tschermak. The chief constituent minerals 
are bronzite (37:9 per cent.), olivine (37:7 per cent.), nickel-iron 
(18:5 per cent.), troilite (4:1 per cent.).—Dr. G. F. H. Smith exhibited 
cut and rough specimens of synthetical sapphire, recently produced by 
Professor Verneuil, oxides of iron and titanium being the colouring 
agents. 
CORRESPONDENCE. 
THE USE OF THE TERM ‘LATERITE’. 
Srr,—I have read Mr. T. Crook’s letter in the November number 
of this journal with interest, but fail to see that he has made it easier 
for everyone to agree with him in his use of the term ‘laterite’. Ido 
not say that the engineers of the Malay Peninsula are correct in their 
use of the term. ‘They have not adhered to Buchanan’s definition, 
but have extended it to cover masses of ironstone, which, even had 
they occurred in decomposition products of crystalline rocks, I am 
quite ready to admit would not have been included in the term 
‘laterite’ by the originator. Similarly, I admit that in other countries 
the original definition has been abandoned, which is _ perhaps 
deplorable ; but the question that occurred to me immediately on 
reading Mr. Crook’s remarks was, what reason has he to consider 
himself in a better position as regards the original definition, which 
is conveniently given in his letter, than the rest ? 
The essential point in Buchanan’s definition is the fact that laterite 
‘sets’ when exposed to the atmosphere, and can be used as brick. 
Buchanan also says that it contains a very large quantity of iron in 
the form of red and yellow ochres. Now Mr. Crook says that 
Buchanan attached to the term ‘laterite’ a significance that is in - 
strict agreement with modern usage, by which we must understand 
Mr. Crook’s insistence on the importance of the free aluminium 
hydroxides. I can only take this to mean that in Mr. Crook’s opinion 
the ‘setting’ of laterite is essentially due to the dehydration of the 
aluminium hydroxides, and if Mr. Crook can prove this proposition 
I am prepared to accept his definition as a somewhat obscure 
paraphrase of Buchanan’s definition. At present I am unable to 
accept it as a paraphrase because, although a change from gibbsite 
to the hard but very brittle diaspore may to a small extent account 
for the hardening, it is but reasonable to suppose that in the case of 
Buchanan’s indurated clays containing ‘‘a very large quantity of 
iron”’, the redistribution and partial dehydration of the ferric hydrate 
are the factors that make laterite commercially valuable (vide Manual 
of the Geology of India, p. 379, and Sir Thomas H. Holland’s paper in 
the 1903 volume of the Gror. Mac., pp. 65, 66, and 69). 
It is clear that the original definition of laterite has been generally 
ignored, perhaps because it appealed to an economic rather than 
a scientific point of view. But with that idea of economic value 
